Brought up in Blairgowrie, Perthshire, Chisholm worked as a deep sea diver in the North Sea oil industry in the 1980s before turning to a life of crime.

After quitting his job, he moved to southern Spain and worked his way into the region’s criminal underworld.

He started smuggling cannabis, but had his sights on something more lucrative – cocaine, the drug of choice of the rich and dubbed “white gold”.

“Half a tonne of gold was worth £7m or £8m,” writer Iain F Macleod tells new BBC Alba three-part documentary Cocaine and the Klondykers.

“Half a tonne of cocaine was worth £100m.”

Chisholm formed a plan to get cocaine of high purity directly to Scotland.

He would land it in the Scottish Highlands, a large and sparsely populated region too big for the authorities to watch every way in and out.

His scheme circumnavigated the existing route of drugs to Scotland through continental Europe, over the sea from Holland to England and then north.

There were too many opportunities for police to intercept consignments.

And by the time cocaine reached Scotland it had been cut – mixed – several times with additives such as flour or baking soda to bulk up the supply.